Reword code comments in plain technical language

Comments only, no code changes. Replaces vague or personified phrasing
with explicit statements of what the code does and why, uses bullet
lists for multi-case behavior, and fixes the settings path in
WindowSettings.h (~/.config/sloposk/sloposk.conf).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/layout/KeymapKeys.h

@@ -34,5 +34,5 @@ struct KeymapKeys {
 
 KeymapKeys readKeymapKeys(xkb_keymap *keymap, quint32 layoutIndex);
 
-// What a dead key shows and types when nothing composes: ´ for dead_acute.
+// Spacing accent for a dead keysym, used as its label and when nothing composes: ´ for dead_acute.
 QString deadKeyText(quint32 keysym);